What is the difference between fire and fire/smoke dampers?

This article explores the key differences between damper classifications; how these might impact on occupant life safety in the event of a fire and; therefore, the best type of damper to choose for a particular part of a building.

What are fire dampers?

Fire dampers are installed in walls, floors or ceilings where a duct/opening penetrates a fire barrier. They are designed to close automatically when thermally activated in the event of a fire. The British Standards 9999:2017 (BS 9999:2017) Code of Practice says that they must be installed to protect any grille or opening through the ductwork enclosure used for ventilation purposes. When they are working properly, they are effective in reducing the speed at which fires spread through a building, minimising the risk of damage and deaths.

What is the purpose of a fire damper?

The primary function of fire dampers is to prevent the spread of fire from one compartment to another. For this reason, a ‘fire damper’ MUST fail-safe close. This must be through a thermal activation element, such as a thermally reactive cassette mechanism or a thermal fuse connected to an electronic actuator.

In order for a damper to work correctly, it is essential for it to be installed and maintained correctly. It goes without saying that a closed damper will be completely ineffective if air, fire and smoke is allowed to pass between the damper and the wall. For this reason, you must always follow manufacturer’s guidance on positioning, installing and fire stopping a fire damper.

In the UK, there are two main classifications of damper, and this differentiates whether a damper is ‘fire’ or ‘fire/smoke’. Generally, fire dampers are ‘E’ classified (fire integrity) and fire/smoke dampers are ‘ES’ classified (fire integrity and reduced smoke leakage).

‘E’ classified dampers - Fire

These dampers have been tested for their integrity and are classified if they can operate in certain conditions. They are generally activated using a thermal ‘chain and link’ or with a cassette mechanism (as on the Actionair FireShield damper).

These dampers will close at approximately 72°C once hot smoke/fire causes the fuse in the thermal activation mechanism to trigger. Due to the damper’s folded blade pack, there is no seal between the blades and damper casing. This means that some smoke leakage can occur, even when the damper is shut. For this reason, the damper cannot be classified as protecting a building and its occupants from smoke.

‘E’ classified dampers are still high quality and high performing fire safety equipment, and they are a viable choice for certain applications. Fire dampers activated only by fusible links are not suitable for protecting escape routes, as outlined in Approved Document B - Volume 2.

‘ES' classified dampers - Fire/Smoke

Fire/smoke dampers work with exactly the same principles as a fire damper; ‘fail safe close’ but with the added safety feature of reduced smoke leakage. They can be thermally activated at 72°C, triggered by a suitable fire detection system or with power failure. In the case of our SmokeShield PTC™, this role is fulfilled by the actuator (control mode) and ETR (Electro Thermal Release).

The biggest difference in performance between an ‘E’ and an ‘ES’ damper is the construction. The ‘ES’ classified damper is constructed with tight fitting blades & seals that will protect escape routes and compartments from fire, and reduce smoke leakage for its classified time (i.e. ES120 - 120 minutes).

These dampers are desirable in any project, but essential when protecting escape routes and sleeping risk - especially when the biggest killer in building fires tend to be the smoke and not the fire. They are most commonly used in hotels, care homes, hospitals and tall buildings.

Most ‘ES’ classified dampers will use an actuator to control the damper. This means that not only will the damper fail-safe close with the thermal fuse, but the damper can be triggered by the Fire Alarm when smoke is detected in the building, or power failure. It is especially easy to configure when a dedicated damper control panel is used. Subsequently, this will reduce the level of cold smoke entering a compartment, giving occupants further time to evacuate the building before smoke enters the room. The dampers not only stop hot smoke, but they can stop the passage of cold smoke too.

Regardless of the type of damper chosen it is KEY that the damper is located correctly in a building and installed as per the manufacturer's instructions (tested by a 3rd party notified body), with sufficient access to perform regular inspections, testing and maintenance.